The instant invention involves a pharmaceutical formulation for bulk composition and oral dosage units comprised of the combination of a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, particularly simvastatin, with a cholesterol absorption inhibitor, particularly ezetimibe, or pharmaceutically acceptable salts, solvates or esters of these compounds, which is useful for lipid management and for preventing and treating atherosclerotic diseases and related conditions and disease events.
It has been clear for several decades that elevated blood cholesterol is a major risk factor for coronary heart disease (CHD), and many studies have shown that the risk of CHD events can be reduced by lipid-lowering therapy. Prior to 1987, the lipid-lowering armamentarium was limited essentially to a low saturated fat and cholesterol diet, the bile acid sequestrants (cholestyramine and colestipol), nicotinic acid (niacin), the fibrates and probucol. Unfortunately, all of these treatments have limited efficacy or tolerability, or both. Substantial reductions in LDL (low density lipoprotein) cholesterol accompanied by increases in HDL (high density lipoprotein) cholesterol could be achieved by the combination of a lipid-lowering diet and a bile acid sequestrant, with or without the addition of nicotinic acid. However, this therapy is not easy to administer or tolerate and was therefore often unsuccessful except in specialist lipid clinics. The fibrates produce a moderate reduction in LDL cholesterol accompanied by increased HDL cholesterol and a substantial reduction in triglycerides, and because they are well tolerated these drugs have been more widely used. Probucol produces only a small reduction in LDL cholesterol and also reduces HDL cholesterol, which, because of the strong inverse relationship between HDL cholesterol level and CHD risk, is generally considered undesirable. With the introduction of lovastatin, the first inhibitor of HMG-CoA reductase to become available for prescription in 1987, for the first time physicians were able to obtain large reductions in plasma cholesterol with very few adverse effects.
Recent studies have unequivocally demonstrated that lovastatin, simvastatin and pravastatin, all members of the HMG-CoA reductase inhibitor class, slow the progression of atherosclerotic lesions in the coronary and carotid arteries. Simvastatin and pravastatin have also been shown to reduce the risk of coronary heart disease events, and in the case of simvastatin a highly significant reduction in the risk of coronary death and total mortality has been shown by the Scandinavian Simvastatin Survival Study. This study also provided some evidence for a reduction in cerebrovascular events.
Despite the substantial reduction in the risk of coronary morbidity and mortality achieved by simvastatin, the risk is still substantial in the treated patients. For example, in the Scandinavian Simvastatin Survival Study, the 42% reduction in the risk of coronary death still left 5% of the treated patients to die of their disease over the course of this 5 year study. Further reduction of risk is clearly needed.
Certain hydroxy-substituted azetidinones such as ezetimibe (described in U.S. Pat. Nos. 5,767,115 and Re. 37721) are now known to be useful as hypocholesterolemic agents in the treatment and prevention of atherosclerosis. Cholesteryl esters are a major component of atherosclerotic lesions and the major storage form of cholesterol in arterial wall cells. Formation of cholesteryl esters is also a key step in the intestinal absorption of dietary cholesterol. Thus, inhibition of cholesteryl ester formation and reduction of serum cholesterol is likely to inhibit the progression of atherosclerotic lesion formation, decrease the accumulation of cholesteryl esters in the arterial wall, and block the intestinal absorption of dietary cholesterol.
Further risk reduction can be achieved with a combination therapy comprised of an HMG-CoA reductase inhibitor such as simvastatin with a cholesterol absorption inhibitor such as ezetimibe to provide lipid management, and to treat or reduce the risk of atherosclerotic disease; the combined use of these two active agents is described in U.S. Pat. No. 5,846,966. Since ezetimibe can be given orally once daily, like HMG-CoA reductase inhibitors such as simvastatin, it would be beneficial to combine the two active agents into a single orally administerable pharmaceutical dosage unit such as a tablet using a formulation that is stable and minimizes the degradation of the active agents.
The instant invention addresses this need by providing a novel formulation for bulk pharmaceutical composition and for oral pharmaceutical dosage units comprised of simvastatin and ezetimibe that can be produced in a robust process that provides a high quality finished product with minimal unwanted degradation by-products and desirable shelf-life stability.